class Array

[1, 2, 3, 4].uniq_by { |i| i.odd? } # => [1, 2]

Returns a unique array based on the criteria in the block.

*DEPRECATED*: Use Array#uniq instead.

def uniq_by(&block)
  ActiveSupport::Deprecation.warn 'uniq_by is deprecated. Use Array#uniq instead'
  uniq(&block)
end